2012 – Year of Rain: Review of Work to Benefit European Otter (Lutra Lutra)

MulkearLIFE’s work with European Otter (Lutra Lutra) is focused on several overlapping themes, namely improving water quality, enhancing the abundance of food resources, creating additional prime habitat, catchment wide survey work and the installation of artificial otter holts. All aspects of the Project’s work is designed to reverse the decline in the otter population in the Lower Shannon Special Area of Conservation.

One of Ireland’s most elusive mammals (Image: John Murphy)

In the Year of Rain, 2012 got off to an excellent start when upwards of twenty members of the Mulkear Conservation Volunteers gathered to install an artificial otter holt in the upper Mulkear catchment. The installation of the recycled plastic holt took place at a site on the Upper Newport River which has been surveyed over the past three years. A total of eight artificial otter holts have been installed to date with plans to install up to 6 more in the coming year at strategically important sites throughout the catchment.

The habitat improvement work has to date focused primarily on sites where habitat has been lost or significantly degraded. The need for such work arises out of the fact that the Mulkear catchment has been subjected to drainage works for well over one hundred years, starting in 1874. These works have had a very considerable impact on riparian vegetation and riverbanks with a concurrent negative impact on otter habitat. In 2012, aside from the project’s instream works which are reviewed separately on tis website, habitat improvement works have taken place at 12 different sites, ranging from large-scale works, like those undertaken above Bilboa Bridge, to the planting of hundreds of native Irish trees at important HNV sites.

Tree planting, main Mulkear River, March 2012 (Image: Glen Wightman)

The otter is one of Ireland’s most elusive mammals and is very rarely seen. It is usual that all one gets to see is a flash of brown followed by the sound of a splash into the water, as otters are at home in their watery world. They are extremely well adapted to their water world, are excellent swimmers, have large lungs and can stay under water for several minutes. On the surface, they swim low in the water, with only their front head visible above water. Otters eat a wide variety of food and essentially will consume what is on offer. They feed mainly on fish (salmon, trout, sea lamprey, and eels), crayfish and small mammals (frogs). The otter population in Ireland is of national and European importance. The otter is protected under the Irish Wildlife Acts (1976 & 2000) and is listed on Annexes II and IV of the EU Habitats Directive. This obliges Ireland to protect the species and undertake regular surveillance and to report regularly on the conservation status of otter in Ireland. While otter are found throughout Ireland, the species was deemed to be in poor conservation status in the most recent Article 17 report.

The unprecedented levels of summer rainfall affected the Project’s work with otter in 2012. More worryingly, there is also little doubt, the persistent flood conditions from June through to early September impacted seriously on otters in the catchment and young otter pups (or whelps) in particular. One would assume the selection of a site for a natal holt would be away from all and every possible risk of flooding. This is not always possible as evidenced by the fact that one of the eight holts installed by MulkearLIFE was partially flooded (while not is use) this summer.

One would hope that natural sites selected by female otters for their natal holts were better selected. While births thankfully occur throughout the year, the extreme flooding this summer is likely to have resulted in pups being lost (circumstantial, survey and observational evidence). The other difficulty otters faced this year was sourcing food during flood events. European otters must eat 15% of their body weight a day. While the summer flood events brought in significant numbers of salmon and extremely large fish, otters faced the additional difficulty of sheer volume and velocity and water discoloration especially, on the main channel of the Mulkear.

Young otter whelp on the banks of the Shannon River (Image: Ruairí Ó Conchúir)

MulkearLIFE had to cancel the Project’s scheduled otter training workshop and survey work in June due to weather conditions. The rivers were simple unsafe for survey purposes and all evidence of otter (Footprints, otter spraints and other evidence) had been washed away.

The 2012 survey work was rescheduled to late July and was preceded by a training workshop, which provided in-house and field based training in otter survey methodology and identification for MCV members. The workshop also served as a useful refresher course for those who had surveyed in 2010 and 2011. In total, 86 sites were included in the 2012 survey covering the entire catchment of 650sq Km. The sites included the following rivers, tributaries and streams: Mulkear, Bilboa, Dead, Newport, Killeengarriff, Clare, Annagh, Reask, Pope’s, Cauteen, Cahernahallia, Dooglasha, Small, Cully, Ahboy and Glaisclluainarbhaoile. Other smaller streams were also included. The vast majority of the sites surveyed were under bridges, along riverbanks, at weirs, fords, culverts or along drainage channels.

The work was undertaken by a total of nine teams over a two-day period in late July, with a minimum of two and up to three per team. In addition to MulkearLIFE staff, the teams included colleagues from Inland Fisheries Ireland, the National Parks & Wildlife Service and a large number of Mulkear Conservation Volunteers (MCV).

Despite the fact that the 2012 survey was undertaken in near perfect weather conditions, the unprecedented rainfall in the seven weeks preceding the survey impacted negatively on the overall findings. Much of the evidence one would normally expect to find was ease was more difficult to find.

This notwithstanding the overall survey results were excellent, with evidence found at a large number of sites, especially those in the upper catchment. The provisional results for 2012 indicate that evidence of otter activity, in the form of an actual sighting, prints or spraint (dried fragments, dried intact or not fully dry) was recorded at 64% of all sites. This is slightly down on 2010 but comparable with 2011.

Best evidence found under bridges, site on the Clare River (Image: Ruairí Ó Conchúir)

Evidence of mink activity was significantly down. number of sites especially in the upper catchment. With evidence of mink activity, in the form of an actual sighting, prints or spraint (dried fragments, dried intact, not fully dry) at only 18% of all sites. This lower figure may be a result of the concerted efforts of local gun clubs and wildlife enthusiasts to control mink numbers in the catchment. The weather may also have been a factor.

This year’s survey findings will continue to help guide the Project’s work in terms of the placement of artificial otter holts and the creation of habitat for otter.

Otters have survived in Irish rivers for thousands of years (Image: Eddie Dunne NPWS)

MulkearLIFE looks forward to 2013 and our ongoing work with otter. A big thank you to all who helped progress our work in 2012. Otters have survived for thousands of years in Irish rivers including during times of flood. MulkearLIFE will continue to work to ensure that the population in the Mulkear catchment remains healthy and vibrant.

There are significant reports on European Otter on the MulkearLIFE website in the ‘Reports & Resources’ section: